This invention relates generally to an improved mechanism and method for pumping fluid, with its primary application to raising subterranean fluid to the surface, at a substantial reduction in the energy required to do so, by means of combining a stroke piston chamber, containing a sufficient volume of fluid, completely isolated from the subterranean fluid but communicating with the under surface of the pump piston top, so that its head pressure is equal to the head pressure in the fluid out-put chamber, which results in the force (Psi) exerted upon the upper surface of the pump piston top being equal to the force (Psi) exerted upward upon the under surface of the pump piston top, while the pump piston base is totally isolated from the stroke piston chamber fluid by a pressure barrier, having a linear pre-load spring, of sufficient elasticity to overcome the seal friction and positively move the pump piston base to the bottom of its stroke, spanning the distance from it to the top surface of the pump piston base.
This invention is an improvement over my invention which is the subject of U.S. Pat. No. 4,834,620, issued May 30, 1989, and is applicable to much deeper wells.
It is known that the rigid drive components of pumps can be replaced with columns of fluid. See W. G. Corey U.S. Pat. No. 1,532,231, J. J. Ceverha U.S. Pat. No. 2,014,613, R. H. Dickinson U.S. Pat. No. 2,490,118 and C. H. Koster U.S. Pat. No. 5,188,517. It is also known that the force exerted by a column of fluid, subject to gravity or some other accelerator, or the hydrostatic head can be balanced by the force of another column of fluid subject to an accelerator. See J. J. Ceverha U.S. Pat. No. 2,014,613, R. J. Hardy U.S. Pat. No. 2,376,538, B. Lee U.S. Pat. No. 4,421,463, and C. R. Canalizo U.S. Pat. No. 4,551,075.
The pumps having balanced columns of fluid either have required energy to lift the hydrostatic head on each direction of the stroke, i.e. W. G. Corey U.S. Pat. No. 1,532,231 and B. Lee U.S. Pat. No. 4,421,463 or have two faces of the pumping mechanism which each lift the hydrostatic head in the same direction, i.e. J. J. Ceverha U.S. Pat. No. 2,014,613 and C. R. Canalizo U.S. Pat. No. 4,551,075. Further limitations of the prior art include too great a force being applied to the pump components when the pressure on the power fluid column is released and their travel is mechanically stopped, lack of isolation of the power fluid from the production fluid, and the inability to easily add additional fluid to the power fluid column.
It is an object of this invention to provide a single stroke pump which can move a column of fluid against an hydrostatic head a variable distance, using significantly less energy that the prior art due to moving the hydrostatic head only once and only the distance of the stroke of the single stroke power piston.
It is a further object of this invention to provide an hydraulic pump as in the preceding object wherein the reduction in hydrostatic head, from fluid ejected from the column of production fluid by the movement of the pump, and the resistance of seals and friction are over come by a pre-load linear spring which returns the pump to its position of rest when the stroke piston returns to its starting position.
Another object is to provide an hydraulic pump according to the preceding object wherein there is provision for a replenishment valve in the power piston to replace any fluid inadvertently or intentionally by-passing the high pressure seals.
Another object of this invention is to provide a single stroke hydraulic pump, wherein the stroke piston is powered in one direction only and at the completion of the single stroke all power is removed from the piston so it is free to return to the starting position, with the columns of production and power fluid being so balanced that the at rest, starting, position of the stroke piston is at a point at which the power column is balanced to the production column, thus the production piston is moved into the recharge position only by the force of the pre-load spring and not the entire hydraulic head of the production column, resulting in minimal stress upon the stop of the production piston when it reached the limit of its travel.
A further object of this invention is to provide a single stroke hydraulic pump as in the preceding object wherein the fluid in the power column is completely isolated from the production fluid so that its density may be varied or the shape of the power column may be varied so long as the total force upon the side of the production piston opposite to the production fluid, remains the same.
A further object of this invention is to provide a method of using a pressurized volume of fluid to balance and equally off-set the static pressure exerted opposing the movement of a volume of fluid by a piston, wherein the volume of fluid to be moved will be reduced in volume by the movement, which volume will be replaced from ambient fluid when the piston is moved in the opposite direction by a pre-charge means, wherein the pre-charge means and the pressurized volume of fluid to balance and equally off-set are isolated from the volume of fluid to be moved.
Other objects, features and advantages of the invention will be apparent from the drawings, the specification and the claims.